1. Field of the Invention
This invention relates to a parking assistance apparatus for assisting a driver in parking a vehicle in parallel parking, back-in parking, etc.
2. Background Art
In recent years, a parking assistance apparatus for assisting a driver in parking a vehicle in parallel parking or putting the vehicle in a garage has been developed.
For example, JP-A-2000-118334 discloses an art of assuming that a position having a predetermined positional relationship with the vehicle position when a driver operates a parking assistance switch is a parking position, computing a recommended path from the current position to the parking position, and telling the driver necessary information for running along the recommended path from a loudspeaker by voice.
JP-A-2000-335436 discloses an art wherein as a driver stops a vehicle so that a predetermined mark (a mark put on the inside of a door or a side mirror) becomes a position matching the center line of a garage and turns on a parking assistance switch, automatic steering control is performed from the vehicle stop position to a parking position based on a previously stored move path, thereby assisting the driver in parking the vehicle.
The target parking position is predetermined by the position where the driver operates the parking assistance switch, and a path to the target position used in the apparatus is predetermined. Thus the driver always needs to stop the vehicle at a predetermined position (a reference position) and the predetermined position is determined by the position of a parking stall.
However, the difference of the driving skill in individuals or the difference of the viewpoint to the target parking position because of the different seating position in individuals, it is feared that a deviation between the reference position and the driver 's switch operating position may arise. If the deviation in the reference position occurs, the target parking position is shifted and the driver is guided to a different position from the essential target position; this is a problem.
For example, JP-A-2001-180402 discloses an art wherein when a vehicle is backed, a steering start guide is superimposed at the target position in stopping at the steering start position together with an image in the rear of the vehicle provided by a camera on a monitor screen, thereby assisting the driver in parking. Usually, the decision of whether or not an available parking space exists is made by a visual check of the driver when the driver approaches the gateway of the parking space. However, in the art, an indicator is not displayed until the driver backs the vehicle after passing through the gateway of the parking space, the driver cannot decide whether or not the parking space is truly available, and thus the driver feels something is wrong from the usual time and is hard to handle the apparatus.
Since the position of the parking frame as the target is calculated based on an image processing of a white line image captured by the camera, the configuration is complicated. In addition, if the road surface is wet or an obstacle exists on the white line or the white line is hard to recognize because of an adjacent parked vehicle, it is feared that the position of the parking frame as the target will be unable to be precisely calculated. Further, if no white line exists, the position of the parking frame as the target cannot be calculated. Therefore for example, parking assistance cannot be carried out where no white line exists in the parking stall adjacent to a parked vehicle.